/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/PolyPathFunctions.h
Create an open arc around the origin on the XY plane, then transformed by Transform. As it is an open path, the end vertex exactly hits the target EndAngle (so will be positioned on the start vertex if the end aligns to the start)
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="GeometryScript|PolyPath") static [FGeometryScriptPolyPath](API\Plugins\GeometryScriptingCore\GeometryScript\FGeometryScriptPolyPath) CreateArcPath3D ( FTransform Transform, float Radius, int NumPoints, float StartAngle, float EndAngle )